In order to produce the speech sounds that comprise the acoustic signal of human language, a complex set of coordinated muscle movements must be realized. Each speech sound requires that a unique series of movements be performed. For example, the tongue must change shape and/or make contact with various landmarks within the oral cavity, often in a precise sequence of movements. Many people, particularly children, may not be able to effect the particular series of movements necessary to produce a particular speech sound. For these individuals, the improper series of movements may result in distorted speech sounds that affect the overall intelligibility of their speech. The inability to produce commonly acceptable speech patterns in accordance with established norms within a community of speakers is known as an articulation disorder.
Traditional methods for treating articulation disorders use complex visual and verbal cues to indicate correct movement and placement of the oral articulators. However, speech sounds requiring proper tongue position, shape, and movement are difficult to teach because the required tongue position, shape, and movement take place behind the teeth and are difficult to show to a patient. As a result it is difficult for patients to assimilate these types of complex motor patterns when taught with traditional visual and verbal cues. In particular, complex verbal cues used to teach proper tongue shape and movement may be difficult for younger patients to process.